Conventional coilers are provided with devices for controlling or maintaining constant the tension acting upon the coiled element with relatively expensive pendulously displaceable rolls or dancer rolls which bear upon the material to be coiled and are provided upstream of the coiler. Uncoiling units, units from which a continuous element such as a web or strand is drawn off a coil, can also be provided with a tensioning device for maintaining a predetermined tension in that element as it is fed to a processing operation downstream of the uncoiler.
Such devices for controlling the tension or maintaining the tension constant in webs or strands of materials in conjunction with coiling and uncoiling units are illustrated and described, for example, in German application 24 24 302 and in German open application 22 32 496. The mechanical construction of such tension-control devices makes them relatively expensive while the comparatively large number of deflection rolls about which the flexible element must pass imparts an excessive friction to the device, making the device unsuitable for many purposes. The devices are not readily adjustable for various tensions.
Another drawback of such earlier devices is that they are dependent for proper function upon a particular orientation and cannot be mounted with any wide range of application. For example, they cannot be readily mounted on the web or stand applicator arm of conventional coiling apparatus. As a consequence, it has been difficult, if not impossible, heretofore to retrofit coilers with such tension control devices.